IOBUFDS_INTERMDISABLE - IOBUFDS_INTERMDISABLE - 2026.1 English - Primitive: Differential Bidirectional Buffer With Input Buffer Disable and On-die Input

Primitive: Differential Bidirectional Buffer With Input Buffer Disable and On-die Input

PRIMITIVE_GROUP: I/O
PRIMITIVE_SUBGROUP: BIDIR_BUFFER

Introduction

The IOBUFDS_INTERMDISABLE primitive is available in the HD I/O banks. It has an IBUFDISABLE port that can be used to disable the input buffer during periods when the buffer is not being used. The IOBUFDS_INTERMDISABLE primitive also has an INTERMDISABLE port that can be used to disable the optional on-die receiver termination feature.

The IOBUFDS_INTERMDISABLE primitive can disable the input buffer and force the O output to the internal logic to a logic-Low when the IBUFDISABLE signal is asserted High and the output buffer is 3-stated (T = High). The USE_IBUFDISABLE attribute must be set to TRUE and SIM_DEVICE to the appropriate value for this primitive to have the expected behavior that is specific to the architecture. If the I/O is using the on-die receiver termination feature, this primitive disables the termination legs whenever the INTERMDISABLE signal is asserted High and the output buffer is 3-stated. When the output buffer is 3-stated (T = High), the input buffer and any on-die receiver termination are controlled by IBUFDISABLE and INTERMDISABLE, respectively. When the output buffer is not 3-stated (T = Low), the input buffer and on-die receiver termination are disabled and the O output (to the internal logic) is forced to a logic-Low. These features can be combined to reduce power whenever the input is idle for a period of time.

I/O attributes that do not impact the logic function of the component, such as IOSTANDARD, DIFF_TERM, and IBUF_LOW_PWR, should be supplied to the top-level port via an appropriate property.

Port Descriptions

Port	Direction	Width	Function
I	Input	1	Input of OBUF. Connect to the logic driving the output port.
IBUFDISABLE	Input	1	Disables input path through the buffer and forces to a logic Low. This feature is generally used to reduce power at times when the I/O is idle for a period of time.
INTERMDISABLE	Input	1	Control to enable/disable on-chip input termination. This is generally used to reduce power in long periods of an idle state.
IO	Inout	1	Bidirectional diff_p port to be connected directly to top-level inout port.
IOB	Inout	1	Bidirectional diff_n port to be connected directly to top-level inout port.
O	Output	1	Output path of the buffer.
T	Input	1	3-state enable input signifying whether the buffer acts as an input or output.

Design Entry Method

Instantiation	Yes
Inference	No
IP and IP Integrator Catalog	No

Available Attributes

Attribute	Type	Allowed Values	Default	Description
SIM_DEVICE	STRING			Set the device version for simulation functionality.
USE_IBUFDISABLE	STRING	"TRUE", "FALSE", "T_CONTROL"	"TRUE"	Set this attribute to "TRUE" to enable the IBUFDISABLE pin.

VHDL Instantiation Template

Unless they already exist, copy the following two statements and paste them before the entity declaration.

Library UNISIM;
use UNISIM.vcomponents.all;


-- IOBUFDS_INTERMDISABLE: Differential Bi-directional Buffer with Input Termination
--                        and Input path enable/disable
--                        May only be placed in High Range (HR) Banks
--                        7 Series
-- Xilinx HDL Language Template, version 2026.1

IOBUFDS_INTERMDISABLE_inst : IOBUFDS_INTERMDISABLE
generic map (
   DIFF_TERM => "FALSE", -- Differential termination (TRUE/FALSE)
   IBUF_LOW_PWR => "TRUE", -- Low Power - TRUE, HIGH Performance = FALSE
   IOSTANDARD => "BLVDS_25", -- Specify the I/O standard
   SLEW => "SLOW",   -- Specify the output slew rate
   USE_IBUFDISABLE => "TRUE") -- Use IBUFDISABLE function "TRUE" or "FALSE"
port map (
   O => O,     -- Buffer output
   IO => IO,   -- Diff_p inout (connect directly to top-level port)
   IOB => IOB, -- Diff_n inout (connect directly to top-level port)
   DCITERMDISABLE => DCITERMDISABLE, -- DCI Termination enable input
   I => I,     -- Buffer input
   IBUFDISABLE => IBUFDISABLE, -- Input disable input, high=disable
   INTERMDISABLE => INTERMDISABLE, -- Input termination disable input
   T => T      -- 3-state enable input, high=input, low=output
);

-- End of IOBUFDS_INTERMDISABLE_inst instantiation

Verilog Instantiation Template


// IOBUFDS_INTERMDISABLE: Differential Bi-directional Buffer with Input Termination
//                        and Input path enable/disable
//                        May only be placed in High Range (HR) Banks
//                        7 Series
// Xilinx HDL Language Template, version 2026.1

IOBUFDS_INTERMDISABLE #(
   .DIFF_TERM("FALSE"),     // Differential Termination ("TRUE"/"FALSE")
   .IBUF_LOW_PWR("TRUE"),   // Low Power - "TRUE", High Performance = "FALSE"
   .IOSTANDARD("BLVDS_25"), // Specify the I/O standard
   .SLEW("SLOW"),           // Specify the output slew rate
   .USE_IBUFDISABLE("TRUE") // Use IBUFDISABLE function, "TRUE" or "FALSE"
) IOBUFDS_INTERMDISABLE_inst (
   .O(O),     // Buffer output
   .IO(IO),   // Diff_p inout (connect directly to top-level port)
   .IOB(IOB), // Diff_n inout (connect directly to top-level port)
   .I(I),     // Buffer input
   .IBUFDISABLE(IBUFDISABLE),     // Input disable input, high=disable
   .INTERMDISABLE(INTERMDISABLE), // Input termination disable input
   .T(T)      // 3-state enable input, high=input, low=output
);

// End of IOBUFDS_INTERMDISABLE_inst instantiation

Related Information

7 Series FPGAs SelectIO Resources User Guide (UG471)

IOBUFDS_INTERMDISABLE - IOBUFDS_INTERMDISABLE - 2026.1 English - Primitive: Differential Bidirectional Buffer With Input Buffer Disable and On-die Input - UG953